The present invention relates to an image recording apparatus having a recording head on which a plurality of recording sections are arranged dotted line-like in one or a plurality of rows; a moving means for relatively moving the recording head and an image recording medium; and a control means for controlling each recording section of the recording head so that one pixel is recorded by turning ON or turning OFF recording of the recording section in each of plural times (N times) of recording periods for each recording section of the recording head, the image recording apparatus records an image formed of a large number of pixels by the recording operation of each recording section of the recording head, on the image recording medium which is relatively moved by the moving means.
Conventionally, the following image recording apparatus is widely known: the image recording apparatus having a recording head on which a plurality of recording sections are arranged dotted line-like in one or a plurality of rows; a moving means for relatively moving the recording head and a photosensitive material; and a control means for controlling each light emitting section of the recording head so that one pixel is exposed by turning ON or turning OFF exposing in each of plural times (N times) of exposure periods for each light emitting section of the recording head, the image recording apparatus records an image formed of a large number of pixels by exposure of each light emitting section of the recording head, on the photosensitive material which is relatively moved by the moving means.
As one of these methods, it is considered and tested to record a multi-contrast image by an image recording apparatus in which the length T(m) of each exposure period satisfies the following equation with respect to the elapsed time sequence m (m is an integer not less than 0 and not more than Nxe2x88x921) of each exposure period in recording of each pixel,
T (m)=xcex1xc3x972m
Where, xcex1 is a coefficient of a positive real number independent of m.
When the above equation is satisfied, the elapsed time sequence of each exposure period becomes that arranged sequentially from a short exposure period to a long exposure period, as shown in FIG. 13.
The control means controls each light emitting section of the recording head so that one pixel is recorded by turning ON or OFF the exposure in the m-th exposure period corresponding to the m-th digit data of multi-contrast image data expressed by a plurality of bits, in such a manner that, from multi-contrast image data expressed by a plurality of bits, 1 pixel is recorded by turning ON or OFF the exposure in the 0th exposure period corresponding to the 0th digit data; by turning ON or OFF the exposure in the 1st exposure period corresponding to the 1st digit data; by turning ON or OFF the exposure in the 2nd exposure period corresponding to the 2nd digit data, . . . , and an image is recorded by exposing pixels on the photosensitive material in the image recording apparatus.
However, in this image recording apparatus, it is known that, when an image, which is commonly called gradation in which density is monotonously increased or decreased in a predetermined direction, is exposed on the photosensitive material, a high density line or a low density line which does not originally exist in the gradation image, is generated during recording and becomes conspicuous.
To the inventor""s surprise, not only the above description, but also the following is found: in an image recording apparatus having a recording head on which a plurality of recording sections are arranged dotted line-like in one or a plurality of rows; a moving means for relatively moving the recording head and an image recording medium; and a control means for controlling each recording section of the recording head so that one pixel is recorded by turning ON or turning OFF recording of the recording section in each of plural times (N times) of recording periods for each recording section of the recording head, the image recording apparatus records an image formed of a large number of pixels by the recording operation of each recording section of the recording head, on the image recording medium which is relatively moved by the moving means, when a gradation image is recorded on the image recording medium by an image recording apparatus in which the length T(m) of each recording period satisfies the following equation with respect to the elapsed time sequence m (m is an integer not less than 0 and not more than Nxe2x88x921) of each recording period in recording of each pixel, and in which the control means controls each light emitting section of the recording head so that one pixel is recorded by turning ON or OFF the recording in the m-th exposure period corresponding to the m-th digit data of multi-contrast image data expressed by a plurality of bits, in such a manner that, from multi-contrast image data expressed by a plurality of bits, 1 pixel is recorded by turning ON or OFF the recording in the 0th recording period corresponding to the 0th digit data; by turning ON or OFF the recording in the 1st recording period corresponding to the 1st digit data; by turning ON or OFF the recording in the 2nd recording period corresponding to the 2nd digit data, . . . , then, a high density line or a low density line which does not originally exist in the gradation image, is generated during recording and becomes conspicuous.
T (m)=xcex1xc3x972m
Where, xcex1 is a coefficient of a positive real number independent of m.
An object of the present invention is to prevent a high density line or low density line, which does not exist in a gradation image, from being generated even when the gradation image is recorded on the image recording medium.
As a theme of the present invention, a cause by which a high density line or a low density line which does not exist in the gradation image, is generated during recording and becomes conspicuous, is deeply considered, and as the result, the cause is considered as follows: the length T(m) of each recording period satisfies the following equation with respect to the elapsed time sequence m (m is an integer not less than 0 and not more than Nxe2x88x921) of each recording period in recording of each pixel,
T (m)=xcex1xc3x972m
That is, for example, in the case where an image is recorded according to N-bit image data, when M is a natural number not more than Nxe2x88x921, in most cases, the elapsed time center of gravity of a recording operation of 1 pixel is scarcely changed between both image recording of pixels having the value different by only 1, in such a manner that the elapsed time center of gravity of a recording operation of 1 pixel is scarcely changed between the recording of the pixel having the value of 2Mxe2x88x922 and that of the pixel having the value of 2Mxe2x88x921, and the elapsed time center of gravity of a recording operation of 1 pixel is also scarcely changed between the recording of the pixel having the value of 2M and that of the pixel having the value of 2M+1. In contrast to that, the elapsed time center of gravity of a recording operation of 1 pixel is greatly changed between the recording of the pixel having the value of 2Mxe2x88x921 and that of the pixel having the value of 2M, as shown in FIG. 13. Accordingly, the positional center of gravity of the recording operation of 1 pixel is greatly changed due to the relative movement of the recording head and the image recording medium during that time, as shown by a dashed line in FIG. 14(A), and therefore, the positional center of gravity of a recorded amount of 1 pixel is greatly changed, as shown by a solid line in FIG. 14(A).
Accordingly, it is considered that, when the gradation image is recorded on the image recording medium, although, as shown in FIG. 14, the positional center of gravity of the recorded amount is scarcely changed in most cases between adjoining pixels themselves, the positional center of gravity of the recorded amount largely differs between adjoining pixel having the value of 2Mxe2x88x921 and pixel having the value of 2M, and the shift of the positional center of gravity of the recorded amount becomes large, thereby, the low density line or the high density line (a linear area of the low recorded amount shown in FIG. 14(B)) is generated and becomes conspicuous.
The theme of the present invention is attained by the following items.
Item 1
An image recording apparatus having a recording head on which a plurality of recording sections are arranged dotted line-like in one or a plurality of rows; a moving means for relatively moving the recording head and an image recording medium; and a control means for controlling each recording section of the recording head so that one pixel is recorded by turning ON or turning OFF recording of the recording section in each of plural times (N times) of recording periods for each recording section of the recording head, the image recording apparatus records an image formed of a large number of pixels by the recording operation of each recording section of the recording head, on the image recording medium which is relatively moved by the moving means, wherein the length T(m) of each recording period is not increased monotonously or is not decreased monotonously with respect to the elapsed time sequence m (m is an integer not less than 0 and not more than Nxe2x88x921) of each recording period in recording of each pixel.
By the invention described in Item 1, the elapsed center of gravity of recording of each pixel can be prevented from largely differing from that of each other, and accordingly, the positional center of gravity of recording of each pixel can be prevented from largely differing from that of each other, thereby, generation of a low density line or a high density line by continuously recording the pixel in which the positional center of gravity of the image recording largely differs from each other, can be suppressed.
Incidentally, an example in which the length T(m) of each recording period is not increased monotonously or is not decreased monotonously with respect to the elapsed time sequence m (m is an integer not less than 0 and not more than Nxe2x88x921) of each recording period in recording of each pixel, is shown in FIG. 15. In this connection, in the following example, an image of 8-bit gradation (gradation expressed by 8 digits in the binary system of the 0th bit to the 7th bit) is recorded in each recording period in the image recording apparatus in which 1 pixel is recorded by turning ON or OFF the recording of the recording section in each of recording periods of 8 times (N=8) for each recording section of the recording head. Each recording period corresponds to any bit of 8-bit gradation, and the length TS (n) of the recording period corresponding to the n-th bit (n is an integer not less than 0 and not more than 7) of the 8-bit gradation is expressed by the following equation.
TS (n)=2n
However, of course, the present invention is not limited to such the premise.
FIG. 15(A) shows an example in which a plurality of recording periods to record 1 pixel is arranged in an elapsed time sequence of the recording period corresponding to the 1st bit, the recording period corresponding to the 3rd bit, the recording period corresponding to the 5th bit, the recording period corresponding to the 7th bit, the recording period of the 6th bit, the recording period corresponding to the 4th bit, the recording period corresponding to the 2nd bit, and the recording period corresponding to the 0th bit. The present example is an example in which generation of a low density line or a high density line in image recording of the gradation image can be entirely suppressed.
FIG. 15(B) shows an example in which a plurality of recording periods to record 1 pixel is arranged in an elapsed time sequence of the recording period corresponding to the 6th bit, the recording period corresponding to the 7th bit, after that, in sequence, from the recording period corresponding to the 5th bit to the recording period corresponding to the 0th bit. The present example is an example in which generation of a low density line or a high density line in the recording area for values not less than 26 can be effectively suppressed, for example, generation of a low density line or a high density line between recording of the value an 27 and recording of the value an 27xe2x88x921 in image recording of the gradation image can be suppressed.
FIG. 15(C) shows an example in which a plurality of recording periods to record 1 pixel is arranged in an elapsed time sequence of the recording period corresponding to the 6th bit, the recording period corresponding to the 4th bit, the recording period corresponding to the 2nd bit, the recording period corresponding to the 0th bit, the recording period of the 1st bit, the recording period corresponding to the 3rd bit, the recording period corresponding to the 5th bit, and the recording period corresponding to the 7th bit.
FIG. 15(D) shows an example in which a plurality of recording periods to record 1 pixel is arranged in an elapsed time sequence of the recording period corresponding to the 7th bit, the recording period corresponding to the 5th bit, the recording period corresponding to the 6th bit, and after that, in sequence, from the recording period corresponding to the 4th bit to the recording period corresponding to the 0th bit. The present example is an example in which generation of a low density line or a high density line in the recording area for values not less than 25 and not more than 27xe2x88x921 can be effectively suppressed, for example, generation of a low density line or a high density line between recording of the value of 26 and recording of the value of 26xe2x88x921 in image recording of the gradation image can be suppressed.
FIG. 15(E) shows an example in which the recording period corresponding to the 7th bit, which is the uppermost bit, is divided into a relatively shorter period which is before in a time series, and a relatively longer period which is after in a time series, and a plurality of recording periods to record 1 pixel is arranged in an elapsed time sequence of a portion of the recording period corresponding to the 7th bit, the recording period corresponding to the 6th bit, a portion of the recording period corresponding to the 7th bit, after that, in sequence from the recording period corresponding to the 5th bit to the recording period corresponding to the 0th bit. In this connection, although the recording period corresponding to the 7th bit is divided into 2 periods, because recording ON or recording OFF is the same in these periods, these periods are incorporated and considered to be one recording period. The elapsed time sequence of each recording period in the recording of each pixel is considered by using the center of gravity of image recording of each recording period. Accordingly, in FIG. 15(E), the center of gravity of the recording period corresponding to the 7th bit is after in a time series with respect to the center of gravity of the recording period corresponding to the 6th bit, therefore, the recording period corresponding to the 6th bit, the recording period corresponding to the 7th bit, and after that, in sequence, the recording periods from the recording period corresponding to the 5th bit to the recording period corresponding to the 0th bit, are arranged in elapsed time sequence.
Item 2
The image recording apparatus according to Item 1, wherein, in recording of each pixel, the longest recording period in the plural times of the recording periods includes the elapsed time center of gravity of all of the plural times of recording periods.
In many cases, it is a cause of the conspicuousness of the low density line or the high density line that a positional center of gravity of recording of 1 pixel largely differs between the case where the recording operations is conducted only in the longest recording period in the plural times (N times) of the recording periods (hereinafter, sometimes, the longest recording period in the plural times (N times) of the recording periods is called the longest recording period), and the case where the recording operation is conducted for a value of image data which is lower by 1 than the value of image data when the recording operation is conducted only in the longest recording period (the recording operation is not conducted in the longest recording period). However, according to the invention described in Item 2, it can be made in the recording of each pixel that the elapsed time center of gravity does not largely differ between the elapsed time center of gravity of image recording in the case where the image is recorded only in the longest recording period, and the elapsed time center of gravity in the case where image recording of the value of image data which is lower than the above-described value of image data by 1, is conducted. That is, the positional center of gravity of the image recording can be made so that it is not largely different from each other, and it can be suppressed that the low density line or the high density line becomes conspicuous in the gradation image.
As an example in which, in recording of each pixel, the longest recording period in the plural times (N times) of the recording periods includes the elapsed time center of gravity of all of the plural times(N times) of recording periods, (A), (B), and (E) in FIG. 15 correspond to the example. That is, in FIG. 15 (A), (B), in the recording of each pixel, the recording period corresponding to the 7th bit, which is the longest recording period, exists in the center of all of the plural times of recording periods, therefore, naturally, in the recording of each pixel, the longest period includes the elapsed time center of gravity CGA of all of the plural times of recording periods. Further, in FIG. 15(E), the elapsed time center of gravity CGA of all of the plural times (N times) of recording periods exists in the latter half side of the recording period corresponding to the 7th bit, which is the longest period. (The elapsed time center of gravity CGA exists between the leading time TP3 and the trailing time TP4 of the latter half side of the recording period corresponding to the 7th bit.)
Item 3
The image recording apparatus according to Item 1 or Item 2, in which, in recording of each pixel, the longest recording period in the plural times of the recording periods exists between the second longest recording period and the third longest recording period in a time series.
In many cases, it is a cause of the conspicuousness of the low density line or the high density line that a positional center of gravity of recording of 1 pixel largely differs between the case where the recording operations is conducted only in the longest recording period in the plural times (N times) of the recording periods (hereinafter, sometimes, the longest recording period in the plural times (N times) of the recording periods is called the longest recording period), and the case where the recording operation is conducted for a value of image data which is lower by 1 than the value of image data when the recording operation is conducted only in the longest recording period (the recording operation is not conducted in the longest recording period). However, according to the invention described in Item 3, it can be suppressed in the recording of each pixel that the elapsed time center of gravity of the recording largely differs between that of image recording in the case where the image is recorded only in the longest recording period, and that in the case where image recording of the value of image data which is lower than the above-described value of image data by 1, is conducted. Thereby, the positional center of gravity of the recording of 1 pixel can be suppressed so that it is not largely different from each other, and it can be suppressed that the low density line or the high density line becomes conspicuous.
In this connection, it is judged by the elapsed time center of gravity of each recording period whether, in recording of each pixel, the longest recording period in the plural times of the recording periods exists between the second longest recording period and the third longest recording period in a time series or not. Further, as an example in which, in recording of each pixel, the longest recording period in the plural times of the recording periods exists between the second longest recording period and the third longest recording period in a time series, (A), (B), and (E) in FIG. 15 correspond to the example. That is, in FIG. 15(A) and (B), the recording period corresponding to the 7th bit, which is the longest recording period, exists between the recording period corresponding to the 6th bit, which is the second longest recording period, and the recording period corresponding to the 5th bit, which is the third longest recording period, in a time series. Further, in FIG. 15(E), the elapsed time center of gravity CG7 of the recording period corresponding to the 7th bit, which is the longest recording period, exists between the elapsed time center of gravity CG6 of the recording period corresponding to the 6th bit, which is the second longest recording period, and the elapsed time center of gravity CG5 of the recording period corresponding to the 5th bit, which is the third longest recording period.
Item 4
An image recording apparatus having a recording head on which a plurality of recording sections are arranged dotted line-like in one or a plurality of rows; a moving means for relatively moving the recording head and an image recording medium; and a control means for controlling each recording section of the recording head so that one pixel is recorded by turning ON or turning OFF recording of the recording section in each of plural times (N times) of recording periods for each recording section of the recording head, the image recording apparatus records an image formed of a large number of pixels by the recording operation of each recording section of the recording head, on the image recording medium which is relatively moved by the moving means, wherein the length TA1(m) of the recording period in concerned order in at least one recording section A1 in continuous plural recording sections of the recording head is different from the length TA2(m) of the recording period in concerned order in at least another one recording section A2, with respect to the elapsed time sequence m (m is an integer not less than 0 and not more than Nxe2x88x921) of each recording period in recording of each pixel of the plurality of pixels which form 1 line in the direction perpendicular to the direction of the relative movement.
According to the invention described in Item 4, in the recording of the plurality of pixels forming 1 line, the elapsed time center of gravity of the recording is averaged in the continuous plural recording sections of the recording head, and accordingly the positional center of gravity of the recording is averaged, thereby, even if the gradation image is recorded, generation of the low density or high density line in the recorded gradation image can be suppressed.
In this connection, as the plural number of the continuous plural recording section of the recording head, the natural number not less than 2 and not more than 16 is preferable, and specifically the number not more than 8, and further, not more than 4 is preferable.
An example in which the length TA1(m) of the recording period in concerned order in at least one recording section A1 in continuous plural recording sections of the recording head is different from the length TA2(m) of the recording period in concerned order in another recording section A2, with respect to the elapsed time sequence m (m is an integer not less than 0 and not more than Nxe2x88x921) of each recording period in recording of each pixel of the plurality of pixels which form 1 line in the direction perpendicular to the direction of the relative movement, is shown in FIG. 16. In this connection, in the following example, an example is described in which an image with 8-bit gradation (the gradation expressed by 8 digits from the 0th bit to the 7th bit in the binary system) is recorded in the image recording apparatus in which 1 pixel is recorded by turning ON or turning OFF the recording of the recording section in each of recording periods of 8 times (N=8) for each recording section of the recording head. Each recording period corresponds to any bit of 8-bit gradation and the length TS(n) of the recording period corresponding to the n-th bit (n is an integer not less than 0 and not more than 7) of the 8-bit gradation is expressed by the following equation.
TS(n)=2n
However, of course, the present invention is not limited to such the premise.
FIG. 16(A) shows an example in which, in the recording of the plurality of pixels which form 1 line in the direction perpendicular to the direction of the relative movement, the elapsed time sequence of the recording period (the longest recording period) corresponding to the 7th bit in the plural times of recording periods to record 1 pixel is different between the recording section A1 and the recording section A2. An example is shown in FIG. 16, in which, in the recording section A1 ((1) in FIG. 16), each recording period to record 1 pixel is arranged in the elapsed time sequence, in sequence from the recording period corresponding to the 7th bit to the recording period corresponding to the 0th bit, and in the recording section A2 ((2) in FIG. 16), each recording period to record 1 pixel is arranged in the elapsed time sequence of the recording period corresponding to the 6th bit, the recording period corresponding to the 7th bit, and after that, in sequence from the recording period corresponding to the 5th bit to the recording period corresponding to the 0th bit.
FIG. 16(B) shows an example in which, in the recording of the plural pixels forming one line in the direction perpendicular to the direction of the relative movement, the elapsed time sequence of the plural times of recording periods to record 1 pixel is just the opposite in the recording section A1 and the recording section A2. That is, in the recording section A1 ((1) in FIG. 16), each recording period to record 1 pixel is arranged in the elapsed time sequence, in sequence from the recording period corresponding to the 7th bit to the recording period corresponding to the 0th bit, and in the recording section A2 ((2) in FIG. 16), each recording period to record 1 pixel is arranged in the elapsed time sequence, in sequence from the recording period corresponding to the 0th bit to the recording period corresponding to the 7th bit.
Incidentally, as an example of the recording section A1 and the recording section A2, the following are listed, however, the present invention is not limited to those: the recording sections at the even-numbered order or the recording sections at the odd-numbered order from the one end; the recording sections at the order of the multiple of 4 from one end and the other recording sections; the recording sections at the order of the multiple of 4 from one end and the recording sections at the order of (the multiple of 4+2) from one end; the recording sections at the order of (the multiple of 4+1) from one end and the recording sections at the order of (the multiple of 4+3) from one end, or the like.
Item 5
The image recording apparatus according to Item 4, wherein continuous plural recording sections of the recording head are 2 adjoining recording sections of the recording head.
According to the invention described in Item 5, even when the gradation image is recorded, the elapsed time center of gravity of the recording is averaged in the adjoining recording sections. Accordingly, the positional center of gravity of the recording is averaged, thereby, generation of the low density or high density line in the recorded gradation image can be more effectively suppressed.
Item 6
The image recording apparatus according to Item 4 or Item 5, wherein, with respect to the elapsed time sequence m (m is not less then 0 and not more than Nxe2x88x921), the length TA1(m) of the recording period in concerned order in the recording section A1 is symmetrical with the length TA2(m) of the recording period in concerned order in the recording section A2.
According to the invention described in Item 6, even when the gradation image is recorded, the elapsed time center of gravity of the recording is more appropriately averaged between the recording section A1 and the recording section A2, and accordingly, the positional center of gravity of the recording is more finely averaged, thereby, generation of the low density or high density line in the recorded gradation image can be more effectively suppressed.
In this connection, the description that, with respect to the elapsed time sequence m (m is not less then 0 and not more than Nxe2x88x921), the length TA1(m) of the recording period in concerned order in the recording section A1 is symmetrical with the length TA2(m) of the recording period in concerned order in the recording section A2, means that, with respect to an arbitrary p (p is an integer not less than 0 and not more than Nxe2x88x921),
TA1(p)=TA2(Nxe2x88x921xe2x88x92p) is satisfied.
Incidentally, as an example in which , with respect to the elapsed time sequence m (m is not less then 0 and not more than Nxe2x88x921), the length TA1(m) of the recording period in concerned order in the recording section A1 is symmetrical with the length TA2(m) of the recording period in concerned order in the recording section A2, (B) in FIG. 16 corresponds to that.
Item 7
An image recording apparatus having a recording head on which a plurality of recording sections are arranged dotted line-like in one or a plurality of rows; a moving means for relatively moving the recording head and an image recording medium; and a control means for controlling each recording section of the recording head so that one pixel is recorded by turning ON or turning OFF recording of the recording section in each of plural times (N times) of recording periods for each recording section of the recording head, the image recording apparatus records an image formed of a large number of pixels by the recording operation of each recording section of the recording head, on the image recording medium which is relatively moved by the moving means, wherein the control means controls each recording section of the recording head so that, in the recording of the plural pixels forming 1 line in the direction perpendicular to the direction of the relative movement, the elapsed time center of gravity of all of the plural times of recording periods of at least one recording section of the continuous plural recording sections of the recording head exists in the outside of the range from the top to the last in a time series, of all of the plural times of recording periods of the other recording sections.
According to the invention described in Item 7, the influence of variation of the elapsed time center of gravity of the recording in each pixel is decreased as the whole, thereby, even when the gradation image is recorded, the conspicuousness of the low density or high density line in the recorded gradation image can be suppressed.
In this connection, as the plural number of continuous plural recording sections, a natural number not less than 2 and not more than 16 is preferable and specifically, not more than 8, and further, not more than 4 is preferably.
An example in which, in the recording of the plural pixels forming 1 line in the direction perpendicular to the direction of the relative movement, the elapsed time center of gravity of all of the plural times of recording periods of at least one recording section A1 of the continuous plural recording sections of the recording head exists in the outside of the range from the top to the last in a time series, of all of the plural times of recording periods of the other recording sections A2, is shown in FIG. 17. In this connection, in the following example, an example is described in which an image with 8-bit gradation (the gradation expressed by 8 digits from the 0th bit to the 7th bit in the binary system) is recorded in each recording period in the image recording apparatus in which 1 pixel is recorded by turning ON or turning OFF the recording of the recording section in each of recording periods of 8 times (N=8) for each recording section of the recording head. Each recording period corresponds to any bit of 8-bit gradation and the length TS(n) of the recording period corresponding to the n-th bit (n is an integer not less than 0 and not more than 7) of the 8-bit gradation is expressed by the following equation.
TS(n)=2n
However, of course, the present invention is not limited to such the premise.
FIG. 17(A) shows an example in which, in the recording of the plural pixels forming 1 line in the direction perpendicular to the direction of the relative movement, all of the plural times of recording periods to record 1 pixel of the recording section A2 ((2) in FIG. 17) is arranged in the elapsed time sequence after all of the plural times of recording periods to record 1 pixel of the recording section A1 ((1) in FIG. 17). Accordingly, in the recording of the plural pixels forming 1 line in the direction perpendicular to the direction of the relative movement, the elapsed time center of gravity CGA1 of all of the plural times of recording periods to record 1 pixel of the recording section A1 ((1) in FIG. 17) does not exist in a range from the top to the last, in a time series, of all of the plural times of recording periods to record 1 pixel of the recording section A2 ((2) in FIG. 17), and the elapsed time center of gravity SGA2 of all of the plural times of recording periods to record 1 pixel of the recording section A2 ((2) in FIG. 17) does not exist in a range from the top to the last, in a time series, of all of the plural times of recording periods to record 1 pixel of the recording section A1 ((1) in FIG. 17).
FIG. 17(B) is an example in which, in the recording of the plural pixels forming 1 line in the direction perpendicular to the direction of the relative movement, the recording periods in sequence from the recording period corresponding to the 7th bit to the recording period corresponding to the 4th bit to record 1 pixel of the recording period A1 ((1) in FIG. 17), then, in sequence from the recording period corresponding to the 7th bit to the recording period corresponding to the 4th bit to record 1 pixel of the recording section A2, after that, in sequence from the recording period corresponding to the 3rd bit to the recording period corresponding to the 0th bit of all of the recording sections are arranged in the elapsed time sequence. Accordingly, in the recording of the plural pixels forming 1 line in the direction perpendicular to the direction of the relative movement, the elapsed time center of gravity CGA1 of all of the plural times of recording periods to record 1 pixel of the recording section A1 ((1) in FIG. 17) does not exist in a range from the top to the last, in a time series, of all of the plural times of recording periods to record 1 pixel of the recording section A2 ((2) in FIG. 17).
Incidentally, as an example of the recording section A1 and the recording section A2, the following are listed, however, the present invention is not limited to those: the recording sections at the even-numbered order or the recording sections at the odd-numbered order from the one end; the recording sections at the order of the multiple of 4 from one end and the other recording sections; the recording sections at the order of the multiple of 4 from one end and the recording sections at the order of (the multiple of 4+2) from one end; the recording sections at the order of (the multiple of 4+1) from one end and the recording sections at the order of (the multiple of 4+3) from one end, or the like.
Item 8
The image recording apparatus according to Item 7, wherein, in the image recording for 1 line, the elapsed time center of gravity of all of the plural times of recording periods of one recording section of 2 adjoining recording sections is not in a range from the top to the last in a time series, of all the plural times of recording periods of the other recording section.
According to the invention described in Item 8, the conspicuousness of the low density or high density line in the gradation image can be more effectively suppressed.
Item 9
The image recording apparatus according to Item 7 or 8, wherein the length and the elapsed time sequence of the plural times of recording periods to record 1 pixel concerning all recording sections are the same.
According to the invention described in Item 9, the conspicuousness of the low density line or high line in the gradation image can be suppressed by a simple control.
This example is shown in FIG. 17(A).
Item 10
The image recording apparatus according to any of Items 1 to 6, wherein the control means controls each recording section of the recording head according to image data for the concerned recording section, by selecting a combination of recording ON or recording OFF in the plural times of recording periods for each pixel.
According to the invention described in Item 10, image recording can be finely conducted corresponding to image data.
Item 11
An image recording apparatus having a recording head on which a plurality of recording sections are arranged dotted line-like in one or a plurality of rows; a moving means for relatively moving the recording head and an image recording medium; and a control means for controlling each recording section of the recording head so that one pixel is recorded by turning ON or turning OFF recording of the recording section in each of plural times (N times) of recording periods for each recording section of the recording head, according to image data for the concerned recording section, by selecting a combination of recording ON or recording OFF in the plural times of recording periods for each pixel, the image recording apparatus records an image formed of a large number of pixels by the recording operation of each recording section of the recording head, on the image recording medium which is relatively moved by the moving means, wherein, with respect to arbitrary image data having a value, at least, not less than {fraction (1/10)} of the maximum image data value, an interval between the elapsed time center of gravity of all of the recording periods of the recording ON and the elapsed time center of gravity of all of the plural times of recording periods is not more than 0.25 times of the pixel interval in the direction of relative movement.
In many cases, it is in an area corresponding to image data having a value, at least, not less than {fraction (1/10)} of the maximum image data value that the low density or high density line is generated when the gradation image is recorded. However, according to the invention described in Item 11, with respect to arbitrary image data having a value at least not less than {fraction (1/10)} of the maximum image data value, it can be suppressed that the elapsed time center of gravity of the recording of each pixel is largely different from each other depending on image data. Accordingly, it can be suppressed that the positional center of gravity of the recording of each pixel is largely different from each other depending on image data, and thereby, it can be suppressed that the low density or high density line is generated when the recording whose positional center of gravity is largely different from each other, is continued.
Item 12
An image recording apparatus having a recording head on which a plurality of recording sections are arranged dotted line-like in one or a plurality of rows; a moving means for relatively moving the recording head and an image recording medium; and a control means for controlling each recording section of the recording head so that one pixel is recorded by turning ON or turning OFF recording of the recording section in each of plural times (N times) of recording periods for each recording section of the recording head, according to image data for the concerned recording section, by selecting a combination of recording ON or recording OFF in the plural times of recording periods for each pixel, the image recording apparatus records an image formed of a large number of pixels by the recording operation of each recording section of the recording head, on the image recording medium which is relatively moved by the moving means, wherein, with respect to arbitrary image data having a value, at least, not less than {fraction (1/10)} of the maximum image data value, when image recording is conducted in the continuous plural recording sections of the recording head according to the concerned image data, an interval between the elapsed time center of gravity of all of recording periods of the recording ON of the continuous plural recording sections and the elapsed time center of gravity of all the plural times of recording periods of the continuous plural recording sections, is not more than 0.25 times of the pixel interval in the direction of the relative movement.
In many cases, it is in an area corresponding to image data having a value, at least, not less than {fraction (1/10)} of the maximum image data value that the low density or high density line is generated when the gradation image is recorded. However, according to the invention described in Item 12, when image recording is conducted in the continuous plural recording sections of the recording head according to the concerned image data, with respect to arbitrary image data having a value at least not less than {fraction (1/10)} of the maximum image data value, the elapsed time center of gravity of the recording of the continuous plural recording sections is not different from each other depending on image data, thereby, the positional center of gravity of the recording of the continuous plural recording sections is not different from each other depending on image data. Accordingly, it can be suppressed that the low density or high density line is generated when the recording whose positional center of gravity is largely different from each other, is continued.
In this connection, as the plural number of the continuous plural recording sections, the natural number not less than 2 and not more than 16 is preferable, and specifically, not more than 8, further, not more than 4 is preferable.
Item 13
An image recording apparatus having a recording head on which a plurality of recording sections are arranged dotted line-like in one or a plurality of rows; a moving means for relatively moving the recording head and an image recording medium; and a control means for controlling each recording section of the recording head so that one pixel is recorded by turning ON or turning OFF recording of the recording section in each of plural times (N times) of recording periods for each recording section of the recording head, according to image data for the concerned recording section, by selecting a combination of recording ON or recording OFF in the plural times of recording periods for each pixel, the image recording apparatus records an image formed of a large number of pixels by the recording operation of each recording section of the recording head, on the image recording medium which is relatively moved by the moving means, wherein a range from the top to the last in a time series, of all of the plural times of recording periods of at least 1 recording section of the continuous plural recording sections of the recording head does not overlap with a range from the top to the last in a time series, of all of the plural times of recording periods of the other recording section.
According to the invention describe din Item 13, the influence of the variation of the elapsed time center of gravity of the recording in each pixel is decreased as the whole, accordingly, the influence of the variation of the positional center of gravity of the recording in each pixel is decreased as the whole, thereby, the conspicuousness of the low density or high density line generated when the recording whose positional center of gravity is largely different, is continued, can be suppressed.
In this connection, as the plural number of the continuous plural recording sections, the natural number not less than 2 and not more than 16 is preferable, specifically, not more than 8, and further, not more than 4 is preferable.
Item 14
An image recording apparatus having a recording head on which a plurality of recording sections are arranged dotted line-like in one or a plurality of rows; a moving means for relatively moving the recording head and an image recording medium; and a control means for controlling each recording section of the recording head so that one pixel is recorded by turning ON or turning OFF recording of the recording section in each of plural times (N times) of recording periods for each recording section of the recording head, according to image data for the concerned recording section, by selecting a combination of recording ON or recording OFF in the plural times of recording periods for each pixel, the image recording apparatus records an image formed of a large number of pixels by the recording operation of each recording section of the recording head, on the image recording medium which is relatively moved by the moving means, wherein, when the gradation image is recorded, in an area corresponding to an arbitrary image data having a value at least not less than {fraction (1/10)} of the maximum image data value, an interval of a positional center of gravity of recording between arbitrary pixel groups recorded by the continuous plural recording sections of the recording head adjoining in the direction of the relative movement, recorded on the image recording medium, is not less than 0.75 times and not more than 1.25 times of the pixel interval in the direction of the relative movement.
According to the invention described in Item 14, it can be suppressed that the low density line or the high density line is generated when pixels whose positional center of gravity of image recording is largely different from each other, are continuously recorded.
In this connection, as the plural number of the continuous plural recording sections, the natural number not less than 2 and not more than 16 is preferable, specifically, not more than 8, and further, not more than 4 is preferable.
Item 15
The image recording apparatus according to any of Items 10 to 14, wherein, in 2 adjoining recording sections, when both image data at least corresponding to the concerned recording sections are not more than a predetermined value, the recording periods of recording ON do not overlap with each other in a time series.
According to the invention described in Item 15, the interfering action between adjoining recording sections when the recording periods of recording ON of adjoining recording sections overlap with each other in a time series, can be suppressed, thereby, a fine image can be recorded.
Incidentally, of course, the following are included in a item in which, in 2 adjoining recording sections, when both image data at least corresponding to the concerned recording sections are not more than a predetermined value, the recording periods of recording ON do not overlap with each other in a time series: there is a case in which, in 2 adjoining recording sections, only when both image data at least corresponding to the concerned recording sections are not more than a predetermined value, the recording periods of recording ON of the adjoining recording sections do not overlap with each other in a time series, and when at least one of image data at least corresponding to the concerned recording section exceeds a predetermined value, the recording periods of recording ON of the adjoining recording sections overlap with each other in a time series; or, in 2 adjoining recording sections,(whatever value the image data corresponding to the concerned recording section has), the recording periods of recording ON of the adjoining recording sections do not overlap with each other in a time series, or the like.
Item 16
The image recording apparatus according to Item 15, wherein there is a case in which, in 2 adjoining recording sections, only when both image data at least corresponding to the concerned recording sections are not more than a predetermined value, the recording periods of recording ON of the adjoining recording sections do not overlap with each other in a time series, and when at least one of image data at least corresponding to the concerned recording section exceeds a predetermined value, the recording periods of recording ON of the adjoining recording sections overlap with each other in a time series.
According to the invention described in Item 16, because there is a case in which, when at least one of image data at least corresponding to the concerned recording section exceeds a predetermined value, the recording periods of recording ON of the adjoining recording sections overlap with each other in a time series, high speed image recording can be conducted, and when both image data corresponding to the recording sections in which an interfering action between adjoining recording sections is conspicuous, are not more than a predetermined value, because recording periods of recording ON of the adjoining recording sections do not overlap with each other in a time series, a bad influence of the interfering action between the adjoining recording sections can be suppressed.
Specifically, when the silver halide photographic photosensitive material is exposed, because an influence of variation of the exposure amount is scarcely conspicuous in a low density area or a high density area, a bad influence due to the interfering action between adjoining recording sections can be suppressed so that it is scarcely conspicuous.
Item 17
The image recording apparatus according to Item 15, wherein, in 2 adjoining recording sections, recording periods of recording ON of the adjoining recording sections do not overlap with each other in a time series.
According to the invention described in Item 17, the interfering action between adjoining recording sections when the recording periods of recording ON of the adjoining recording sections overlap with each other in a time series, can be prevented by the simple control, and a fine image can be recorded.
Item 18
The image recording apparatus according to any one of Items 10 to 17, wherein the control means divides each recording section of the recording head into a plurality of blocks so that recording sections which adjoin each other belong to blocks which are different from each other, and controls so that, in both recording sections which belong to blocks different from each other, when both of image data at least corresponding to the concerned recording sections are not more than a predetermined value, the recording periods of recording ON do not overlap with each other in a time series.
According to the invention described in Item 18, it can be conducted simply that, in 2 adjoining recording section, when both of image data at least corresponding to the concerned recording sections are not more than a predetermined value, the recording periods of recording ON do not overlap with each other in a time series. Accordingly, an interfering action exerting between adjoining recording sections when the recording periods of recording ON of the recording sections overlap with each other in a time series, can be suppressed, and a fine image can be recorded.
Item 19
The image recording apparatus according to Item 18, wherein, with respect to the elapsed time sequence m (m is an integer not less than 0 and not more than Nxe2x88x921) of each recording period in recording of each pixel, the length TB1(m) of the recording period of the concerned order in a recording section B1 belonging to one block in the plural blocks is different from the length TB2(m) of the recording period of the concerned order in a recording section B2 belonging to other block.
According to the invention described in Item 19, even when the gradation image is recorded, the elapsed time center of gravity of recording is averaged in the recording sections belonging to the plural blocks, and accordingly, the positional center of gravity is averaged, thereby, generation of the low density or high density line in the recorded gradation image can be suppressed.
Item 20
The Image recording apparatus according to Item 19, wherein, with respect to the elapsed time sequence m (m is an integer not less then 0 and not more than Nxe2x88x921), the length TB1(m) of the recording period of the concerned order in the recording section B1 is symmetrical with the length TB2(m) of the recording period of the concerned order in the recording section B2.
According to the invention described in Item 20, even when the gradation image is recorded, the elapsed time center of gravity of the recording is finely averaged between the recording section B1 and the recording section B2, and accordingly, the positional center of gravity of the recording is finely averaged, thereby, generation of the low density or high density line in the recorded gradation image can be more effectively suppressed.
In this connection, the description in which, with respect to the elapsed time sequence m (m is an integer not less then 0 and not more than Nxe2x88x921), the length TB1(m) of the recording period of the concerned order in the recording section B1 is symmetrical with the length TB2(m) of the recording period of the concerned order in the recording section B2, means that, with respect to an arbitrary p (p is an integer not less than 0 and not more than Nxe2x88x921), TB1(p)=TB2(Nxe2x88x921xe2x88x92p) is satisfied.
Item 21
The image recording apparatus according to Item 19 or 20, wherein, in the recording of each pixel of the plural pixels forming 1 line in the direction perpendicular to the direction of relative movement, the control means controls each recording section of the recording head so that the elapsed time center of gravity of all of the plural times of recording periods of the recording section belonging to at least 1 block of the plural blocks is outside of a range from the top to the last, in a time series, of all of the plural times of recording periods of the other recording sections.
According to the invention described in Item 21, an influence of variation of the elapsed time center of gravity of recording of each pixel is decreased as a whole, thereby, even when the gradation image is recorded, the conspicuousness of the low density or high density line in the recorded gradation image can be suppressed.
Item 22
The image recording apparatus according to any one of Items 1 to 21, wherein the recording section is a light emitting section, the image recording medium is the photosensitive material, the recording period is an exposure period, the recording ON is the exposure ON, and the recording OFF is the exposure OFF.
According to the invention described in Item 22, it can be suppressed that the elapsed time center of gravity of exposure of each pixel is largely different from others, and accordingly, it can be suppressed that the positional center of gravity of exposure of each pixel is largely different from others. Thereby, generation of the low density or high density line caused when pixels in which the positional center of gravity of image recording is largely different from each other, are continuously recorded, can be suppressed.
Item 23
The image recording apparatus according to Item 22, wherein the image recording medium is silver halide photographic photosensitive material.
When a gradation image is recorded, a phenomenon that the high density or low density line which does not exist in the original gradation image, is generated during recording, is conspicuous when the image recording medium is silver halide photosensitive material. However, according to the invention described in Item 23, generation of the low density or high density line caused when an pixel whose positional center of gravity is largely different from others, is continuously recorded, can be suppressed. Further, in the case of silver halide photographic photosensitive material, because variation of the exposure amount is not conspicuous in the low density area and the high density area, an image whose positional center of gravity is largely different from others, may be made so that it is not continuously recorded only in an intermediate density area. Accordingly, the conspicuousness of the low density or high density line caused by continuously recording an image whose positional center of gravity is largely different from others, can be simply prevented.
Item 24
The image recording apparatus according to any one of Items 1 to 23, wherein, with respect to the order n (n is an integer not less than 0 and not more than Nxe2x88x921) of shortness of recording periods in the plural times of recording periods, the length TS(n) of each recording period satisfies the following equation.
TS(n)=xcex1xc3x972n+xcex2(n)+xcex3(n)
Where, xcex1 is a coefficient which does not depend on n, and is a positive real number. xcex2(n) is a positive real number which satisfies xcex2(nxe2x88x921)xe2x89xa7xcex2(n) with respect to an arbitrary n not less than 1, and satisfies
0.1xc3x97xcex1xc3x972Nxe2x88x921 greater than xcex2(0) greater than xcex2(Nxe2x88x921)
and xcex3(n) is a real number whose absolute value is not more than (xcex1xc3x972n+xcex2(n))/100 with respect to an arbitrary n.
According to the invention described in Item 24, an influence of switching characteristics of each recording section can be decreased, and thereby, higher quality image recording can be conducted, and image recording of gradation can be more finely conducted.
Specifically, when the image recording medium is silver halide photographic image recording medium, an influence of a multiple exposure effect and reciprocity law failure characteristics which are specific to silver halide photographic photosensitive material, can be finely corrected, thereby, higher quality image recording can be conducted, and image recording of gradation can be more finely conducted. Explanation of terminology or the like.
As a phrase that a plurality of recording sections are arranged dotted line-like in one or a plurality of rows, the following are cited: as shown by (a) in FIG. 1, a plurality of recording sections are arranged dotted line-like in 1 row; as shown by (b) in FIG. 1, a plurality of recording sections are arranged dotted line-like in 2 lows; as shown by (c) in FIG. 1, a plurality of recording sections are arranged dotted line-like in 3 rows, or the like. In this connection, in (a), (b), (c) in FIG. 1, the plural rows of recording sections are arranged in positions different form each other with respect to the arrangement direction, however, the plural rows of recording sections may be arranged in the same positions. Further, the shape of a dot in a dotted line may be any of circular shape, rectangular shape, triangular shape, or the like. Still further, both of adjoining recording sections arranged dotted line-like may be separated from each other, or in contact with each other.
Further, as the recording head on which a plurality of recording sections are arranged dotted line-like in one or a plurality of rows, the following are listed: an LED array; a vacuum fluorescent printing head (VFPH); a PLZT shutter array fitted before a light source; a liquid crystal array fitted before a light source; a recording head on which a plurality of light emitting sections are arranged dotted line-like in one or plural rows, such as the other end of optical fiber group whose one end is connected to each of recording operation sources, and which is arranged in one or plurality of rows; an ink jet printing head on which a plurality of liquid-drop jetting sections are arranged dotted line-like in one or a plurality of rows; a heating head on which a plurality of heating sections in a thermal sublimation type printer, a thermal transfer type printer, or the like, are arranged dotted line-like in one or plurality of rows; or similar recording heads. Further, as a recording section in a phrase that the recording head on which a plurality of recording sections are arranged dotted line-like in one or a plurality of rows, the following are listed: an LED light emitting element in the LED array; a fluorescent substance light emitting element of the vacuum fluorescent printing head (VFPH); each shutter of the PLZT shutter array fitted before a light source; each liquid crystal shutter of the liquid crystal array fitted before a light source; a light emitting section of the recording head on which a plurality of light emitting sections are arranged dotted line-like in one or plural rows, such as the other end of optical fiber group whose one end is connected to each of recording operation sources, and which is arranged in one or plurality of rows; a liquid-drop jetting section of the ink jet printing head on which a plurality of liquid-drop jetting sections are arranged dotted line-like in one or a plurality of rows; a heating section of the heating head on which a plurality of heating sections in a thermal sublimation type printer, a thermal transfer type printer, or the like, are arranged dotted line-like in one or plurality of rows; or similar recording sections.
Adjoining recording sections means the recording sections which adjoin in the arrangement direction, that is, in FIG. 1(a), the recording section No. 1 and the recording section No. 2 are recording sections adjoining each other, and also the recording section No. 2 and the recording section No. 3 are recording sections adjoining each other; in FIG. 1(b), the recording section No. 1 and the recording section No. 2 are recording sections adjoining each other, and also the recording section No. 2 and the recording section No. 3 are recording sections adjoining each other; and in FIG. 1(c), the recording section No. 1 and the recording section No. 2, and the recording section No. 2 and the recording section No. 3 are recording sections adjoining each other, and also the recording section No. 3 and the recording section No. 4 are recording sections adjoining each other.
The gradation image means an image obtained when an image is recorded by increasing or decreasing the image data value by 1 for every 1 line advancing in the direction of the relative movement.
The control means has preferably a ROM in which the content of control is stored. Thereby, an amount of operations necessary at the time of image recording is reduced, so that high speed image recording can be conducted.
A phrase that, with respect to the elapsed time sequence m (m is an integer not less than 0 and not more than Nxe2x88x921) of each recording periods in recording of each pixel, the length T(m) of the recording period is increased monotonously, means that the length T(m) of each recording period satisfies the following relationship.
T(1)xe2x89xa6T(2)xe2x89xa6 . . . xe2x89xa6T(Nxe2x88x922)xe2x89xa6T(Nxe2x88x921)
Further, A phrase that, with respect to the elapsed time sequence m (m is an integer not less than 0 and not more than Nxe2x88x921) of each recording periods in recording of each pixel, the length T(m) of the recording period is decreased monotonously, means that the length T(m) of each recording period satisfies the following relationship.
T(1)xe2x89xa7T(2)xe2x89xa7 . . . xe2x89xa7T(Nxe2x88x922)xe2x89xa7T(Nxe2x88x921)
Incidentally, the length T(m) of each recording period means the length of time of recording ON or recording OFF in each recording period. For example, in the case of FIG. 15(E), the length T(19 of the recording period corresponding to the 6th bit is the length of time between the top time TP2 and the last time TP3 of the recording period corresponding to the 6th bit because the recording period corresponding to the 6th bit is a continuous period, however, the length T(2) of the recording period corresponding to the 7th bit is the length of time of summation of the length of time between the top time TP1 of the first half portion of the recording period corresponding to the 7th bit and the last time TP2, and the length of time between the top time TP3 of the second half portion of the recording period corresponding to the 7th bit and the last time TP4, because the recording period corresponding to the 7th bit is intermittently divided into the first half portion and the second half portion.
All of the plural times of recording periods means a period in which the plural times of recording periods are collected together. The elapsed time center of gravity of all of the plural times of recording periods means the elapsed time center of gravity of the period in which the plural times of recording periods are collected together. A phrase xe2x80x9cfrom the top to the last, in a time series, of all of the plural times of recording periodsxe2x80x9d means xe2x80x9cfrom the top of the leading recording period in the plural times of recording periods to the last of the trailing recording period in the plural times of the recording periodsxe2x80x9d.